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Impact of Pre-operative weight loss on 30-day complication rates following bariatric surgery
Omnia S. Saleh*1, Youssef Farag2, Pourya Medhati1, Ali Tavakkoli1
1General Surgery, BWH, Boston, MA; 2PGME, Harvard Medical School, Boston, MA

Weight loss prior to bariatric surgery is recommended by many surgeons to help reduce surgical morbidity, particularly in high BMI patients. Data supporting this practice is however limited, and the requirement can delay care and, in some cases, prevent patients from receiving the necessary surgery. Aim of this study was to evaluate the impact of pre-operative weight loss on surgical outcomes after both Lap Sleeve Gastrectomy (LSG) and Lap Roux-en-Y Gastric Bypass (RYGB).

We used the MBSAQIP 2021 date files and selected patients undergoing primary LSG and RYGB and used their highest recorded pre-operative weight and weight immediately prior to surgery to assess weight changes in the peri-operative period. Post-operative complications and procedure times, as well as baseline demographics were collected, and outcomes were compared using a logistic regression model adjusting for age, gender, race, diabetes mellitus, hypertension, ASA class, smoking and sleep apnea.

902 participating bariatric centers in North America.

4.Patients (or Other Participants)
Adult patients undergoing primary RYGB and primary LSG.

5.Interventions (if any)
Based on their pre-operative weight changes patients were divided into 4 groups: those who had not lost or gained weight (0%; reference range); those who had 0-5% total body weight loss (TBWL); those who had 5-10% TBWL; and those who had >10% TBWL prior to surgery.

6. Main Outcome Measures
30-day post-operative complications and operative time.

We included 131,619 patients who underwent LSG and 58,353 who underwent RYGB, with 38,640, not losing or gaining weight prior to surgery while 92,372 had 0-5% TBWL, 46,028 had 5-10% TBWL, and 12,932 lost >10% TBWL.
For both LSG and RYGB, pre-operative weight loss of >10% led to a slight reduction in overall morbidity only in those with BMI >50. No degree of weight loss had any impact on post-operative complications or operative time in those with BMI<50.

Pre-operative weigth loss of >10% led to only a small improvement in post-operative complications in patients with BMI "50 who underwent either LSG or RYGB. For those with BMI<50, no degree of pre-operative weight loss led to any improvement in operative time or post-operative complications. These findings question the common requirement of pre-operative weight loss in lower BMI bariatric patients, which can delay access to surgery and in some cases deter patients from pursuing this treatment.

Overview of Table 1
Numbers%27,246 (20.7%)64,208 (48.8%)31,746 (24.12%)8,419 (6.40%)11,394 (19.53%)28,164 (48.26%)14,282 (24.48%)4,513 (7.73%)
Age, Mean42.5742.5443.7144.6944.0144.4745.5046.19
Gender, Female22,41953,82625,30763879,82324,43311,7893,701
Operative time with BMI " 5070.6 mins71.46 mins
73.52 mins76.52 mins124.01 mins129,6 mins132.6 mins129.2 mins
Operative time with BMI < 5067.1 mins68.1 mins69,2 mins72.1 mins128.7 mins128.7 mins129.9 mins130.4 mins
Complication Rates with BMI " 50167 (2.71%)345 (2.59%)175 (2.85%)35 (2.21%)129 (4.93%)321 (5.29%)174 (5.76%)36 (4.54%)
Complication Rates with BMI <50440 (2.09%)1,158 (2.28%)555 (2.11%)144 (2.11%)488 (5.56%)1,159 (5.24%)603 (5.36%)224 (6.02%)

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